/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.graphics;

import com.example.android.apis.R;

import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.*;
import android.util.FloatMath;

public class BitmapMesh extends GraphicsActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {
		private static final int WIDTH = 20;
		private static final int HEIGHT = 20;
		private static final int COUNT = (WIDTH + 1) * (HEIGHT + 1);

		private final Bitmap mBitmap;
		private final float[] mVerts = new float[COUNT * 2];
		private final float[] mOrig = new float[COUNT * 2];

		private final Matrix mMatrix = new Matrix();
		private final Matrix mInverse = new Matrix();

		private static void setXY(float[] array, int index, float x, float y) {
			array[index * 2 + 0] = x;
			array[index * 2 + 1] = y;
		}

		public SampleView(Context context) {
			super(context);
			setFocusable(true);

			mBitmap = BitmapFactory.decodeResource(getResources(),
					R.drawable.beach);

			float w = mBitmap.getWidth();
			float h = mBitmap.getHeight();
			// construct our mesh
			int index = 0;
			for (int y = 0; y <= HEIGHT; y++) {
				float fy = h * y / HEIGHT;
				for (int x = 0; x <= WIDTH; x++) {
					float fx = w * x / WIDTH;
					setXY(mVerts, index, fx, fy);
					setXY(mOrig, index, fx, fy);
					index += 1;
				}
			}

			mMatrix.setTranslate(10, 10);
			mMatrix.invert(mInverse);
		}

		@Override
		protected void onDraw(Canvas canvas) {
			canvas.drawColor(0xFFCCCCCC);

			canvas.concat(mMatrix);
			canvas.drawBitmapMesh(mBitmap, WIDTH, HEIGHT, mVerts, 0, null, 0,
					null);
		}

		private void warp(float cx, float cy) {
			final float K = 10000;
			float[] src = mOrig;
			float[] dst = mVerts;
			for (int i = 0; i < COUNT * 2; i += 2) {
				float x = src[i + 0];
				float y = src[i + 1];
				float dx = cx - x;
				float dy = cy - y;
				float dd = dx * dx + dy * dy;
				float d = FloatMath.sqrt(dd);
				float pull = K / (dd + 0.000001f);

				pull /= (d + 0.000001f);
				// android.util.Log.d("skia", "index " + i + " dist=" + d +
				// " pull=" + pull);

				if (pull >= 1) {
					dst[i + 0] = cx;
					dst[i + 1] = cy;
				} else {
					dst[i + 0] = x + dx * pull;
					dst[i + 1] = y + dy * pull;
				}
			}
		}

		private int mLastWarpX = -9999; // don't match a touch coordinate
		private int mLastWarpY;

		@Override
		public boolean onTouchEvent(MotionEvent event) {
			float[] pt = { event.getX(), event.getY() };
			mInverse.mapPoints(pt);

			int x = (int) pt[0];
			int y = (int) pt[1];
			if (mLastWarpX != x || mLastWarpY != y) {
				mLastWarpX = x;
				mLastWarpY = y;
				warp(pt[0], pt[1]);
				invalidate();
			}
			return true;
		}
	}
}
